Tape drive actuated open end adjustable wrench

ABSTRACT

Adjustable jaw open end wrench of the type in which the movable jaw is driven by a worm gear, comprising a manual slide actuated drive belt for driving a main drive gear which is in mesh with the drive belt, an intermediate drive gear between the worm gear and the main drive gear, alignment means for holding the worm gear in alignment, tightening means for maintaining the drive belt in taut condition during assembly and operation.

[ Aug. 26, 1975 United States Patent 1 Halls 3,640,159 2/1972 Halls et 81/172 X 3 673 896 7/1972 Vardaman 81/165 TAPE DRIVE ACTUATED OPEN END ADJUSTABLE WRENCH [75] Inventor: Kenneth F. Halls, Denver, Colo. Primary Examiner Al Lawrence Smith [73] Assistant Examiner-James G. Smith Assignee: A. H. Brickley, Denver, Colo. a

part interest Attorney, Agent, or FirmSheridan, Ross & Fields [57] ABSTRACT Adjustable jaw open end wrench of the type in which [22] Filed: Apr. 10, 1974 [21] Appl. No.: 459,533

the movable jaw is driven by a worm gear, comprising [52] U5. 81/170; 81/165 a m n l li actuated riv belt for driving a main [51] Int. B25b 13/16 drive g which is n m h h h drive belt, an n termediate drive gear between the worm gear and the [58] Field of Search............. 81/129, 155, 165, 170,

81 /172 main drive gear, alignment means for holding the worm gear in alignment, tightening means for maintaining the drive belt in taut condition during assembly and operation.

[56] References Cited UNITED STATES PATENTS 3,368,432 2/1968 81/165 19 Claims, 5 Drawing Figures TAPE DRIVE ACTUATED OPEN END ADJUSTABLE WRENCH BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates generally to adjustable jaw open end wrenches, particularly, to this type wrench in which the movable jaw is driven through suitable gears by a drive belt.

2. Prior Art Adjustable jaw open end wrenches are conventionally constructed with a body including a fixed jaw and a movable jaw journaled in the head to move toward and away from the fixed jaw and driven by a worm which is in mesh with a rack attached to the movable jaw. In one type of wrench the movable jaw is adjusted by manually turning the worm with the fingers of the user, in another type the movable jaw is driven by a slide-actuated spiral drive shaft which is drivingly connected to the rack on the movable jaw, and in a third type the spiral driving element is replaced by an endless belt which is drivingly connected to the movable jaw. Illustrative of the wrenches in which the adjustment is made manually is US. Pat. No. 2,755,693. Pat. Nos. 2,753,748 and 3,125,911 disclose wrenches of the second type while Pat. No. 3,368,432 discloses an adjustable jaw wrench in which a movable jaw is driven by an endless belt.

The three type wrenches are subject to the disadvantage that the worm is not held securely in fixed alignment in its recess in the wrench head so that it gyrates around its longitudinal axis resulting in excessive wear and loss of applied power to adjust the width of the gap between the jaws. The first type wrench is also objectionable because of the difficulty of manually turning the worm gear for adjustment and the requirement that the jaws usually cannot be adjusted while they are over the nut with the result that ordinarily several adjustments are necessary to obtain the proper fit. The belt driven wrench shown in Pat. No. 3,368,432 is objectionable because actuating power applied directly to the worm by the drive belt results in a misaligning torque being applied to the worm causing it to bind in its recess with excessive wear and loss of actuating power. A further objection to this type wrench is that there is no way to keep the belt taut both during and after assembly so that assembly of the belt and associated gears into the wrench body is difficult and after assembly there is always the danger of the belt coming off the drive gear. If the belt is not held taut during operation of the wrench there is a lag between movement of the belt and the elements it drives and there is also loss of power.

Accordingly, a principal object of this invention is the provision of a belt driven adjustable jaw wrench in which the worm is not subjected to misaligning torque by the drive belt, the worm is maintained in proper alignment at all times, and the belt is held taut during assembly and operation.

SUMMARY OF THE INVENTION An open end belt-driven adjustable jaw wrench including an intermiediate bevel gear between the drive belt and the worm which is in mesh with the two to prevent misaligning torqueing of the worm, a pin and spring mounted between the worm and the bottom of the recess in which it is seated to hold the worm in proper alignment at all times, and a self-tightening elbow hinged at one end and with its movable end in floating contact through an idler gear with the interior surface of the aft loop of the drive belt to automatically tighten the drive belt upon movement from an angled or inoperative position to an operative position substantially parallel with the longitudinal axis of the wrench. Hereinafter, in the specification and claims said angled and parallel positions will be referred to, respectively, as the inoperative and operative positions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view of the open end adjustable jaw wrench of the invention;

FIG. 2 is an elevational plan view of the wrench of FIG. 1; a

FIG. 3 is a view like FIG. 2 with the top face of the wrench partially cut away; v I

FIG. 4 is a side elevational view of the belt tightening assembly of the wrench; and

FIG. 5 is a sectional view taken on line 5-5 of FIG.

DESCRIPTION OF PREFERRED EMBODIMENT Referring now to FIGS. 1, 2 and 3, the wrench comprises: a body of suitable material such as metal, an integral head 12 having a fixed' jaw 14 integral therewith, a movable jaw 16 journaled for reciprocal movement in the head and a handle 18.

As shown in FIG. 3, the head 12 has a main recess 20 in the form of a slide channel extending transversely through the head and an auxiliary circular recess 22 communicating rearwardly with the main recess 20. Movable jaw 16 is reciprocably mounted in recess or slide channel 20 for reciprocal movement therein in mating alignment with fixed jaw 14 and has a rack 24 machined in its rearwardly facing edge. For driving the movable jaw 16 in reciprocal movement for adjustment of the gap between the movable and fixed jaws, a worm 26 is seated in recess 22 in mesh with rack 24 so that it is drivingly connected to the rack. A bevel gear 28 is machined on the outer end of worm 26 for use in driving the worm and the gear is rotatably seated on thrust shoulder 27. A closure plug 30 threadedly engages the inner wall of recess 22 at its outer end to hold the worm in the recess.

The worm 26 has a central bore 32 for receiving alignment pin 34 and biasingspring 35 with the end of the pin abutting the end of the spring. The pin 34 and the spring 35 are mounted between the bottom of recess 22 and the worm so that the worm is outwardly biased toward closure plug 30 in the properly aligned position in operative orientation at all times.

Housing channel 36 (FIG. 1) for housing the cover plate assembly is machined in the forward half of handle 18 in communication with recess 22 at its forward end and with a shelf or step 38 extending around its periphery. Gripping channel 40 and hanging hole 42 may be provided in the rear half of the handle as an aid for gripping the handle and for hanging it on a wall, respectively.

For driving the worm 26 a drive belt assembly (FIG. 1) is provided comprised of a power transmission element in the form of drive gear 44, meshing drive belt 46, and actuating slide button 48 mounted in the slide channel 36. The drive belt may be in the form of a chain or other driving means. The top of the slide channel is closed by cover plate 50 having top 51. The elements of the cover plate assembly and the manner of their assembly with respect to slide channel 36 will now be described with reference to FIG. 1.

The drive belt assembly is comprised of endless drive belt 46 which is assembled on drive gear 44 provided with lateral teeth 45 and idler gear 52 provided with lateral teeth 53 by looping it over these gears with the formation of fore and aft loops before the drive belt assembly is assembled with cover plate 50 for positioning in slide channel 36 in a manner to be explained later.

The drive belt 46 is preferably made of flexible metal, plastic, or other suitable material, with longitudinally spaced internal laterally extending teeth 54 which mesh with the teeth 45 on drive gear 44 for driving the latter. The teeth 54 also mesh with the teeth 53 on idler gear 52.

Drive gear 44 is comprised of a cylindrical body section 56 carrying the teeth 45 spaced to mesh with the teeth 54 of the drive belt. Bevel gear teeth 58 are machined on the face of the enlarged end 60 of the drive gear 44 for transmitting power from the drive belt 46 to the worm 26.

Cover plate 50 for seating on shelf 38 of slide channel 36 is of flat construction and has a bottom flange 66 depending from its bottom surface and extending partially around its periphery. For receiving the drive gear 44 and the front loop of belt 46 in assembly the flange 66 has circular seating recesses 68 machined in its forward ends of a size requiring slight pressure for seating the shaft of gear 44 therein. A circular locking lip 70 and circular boss 72 are constructed at the fore end of the cover plate for cooperation with the roof 62 of recess 22 for locking the cover plate in slide channel 36. A slide groove or slot 74 in which slide button 48 moves is machined centrally of cover plate 50.

Slide button 48, operable from outside the wrench body for moving drive belt 45, is of oblong construction and has transverse grooves 76 across its saddle-shaped top surface to aid in moving it when it is attached to drive belt 46.

The method will now be described of assembling the cover plate assembly of cover plate 50, slide button 48, drive belt 46, drive gear 44, floating idler gear 52 and elbow 92. In the preferred method of securing drive belt 46 in cover plate 50, the slide button 48 is positioned on top of the cover plate with depending boss 78 seated in slide slot 74. Drive belt 46 is then positioned inside the cover plate 50 with belt hole 80 aligned with slide button hole 82. Lock washer 84 is then positioned on the inside of drive belt 46 with washer hole 86 in alignment with holes 80 and 82 and with lock washer teeth 88 mating with belt teeth 54. This assembly is then secured together by inserting pin 90 through the aligned holes and swaging it in place.

The drive belt tightening mechanism of the cover plate assembly will now be described by reference to FIGS. 1 and 4. For tightening the drive belt 46 and holding it taut for assembly of the cover plate assembly in housing channel 36 and for maintaining the belt taut during use of the wrench after the assembly to keep it on the gears 44 and 52, self-tightening hinged elbow 92 is mounted in depending top flanges 66 by means of axle or elbow mounting pin 94 passing through hole 96 and anchored in holes 98.

For the method of assembly of hinged elbow 92 and idler gear 52 into the cover plate 50 reference is again made to FIGS. 1 and 4. Self-tightening elbow 92 is hingedly secured by its fore end into the depending flanges 66 of cover plate 50 at a point below a line connecting the centers of the belt loops (or centers of gears 44 and 52) when the loops are farthest apart. The assembly is-made by placing the fore end of the elbow between the flanges, inserting pin 94 through mating holes 98 and 96 and securing the pin in place by swaging or otherwise.

With the aft loop of the belt 46 and the aft or free end of elbow 92 angled downwardly in the opposite direction of the top of cover plate 50, the elbow thus being in its inoperative position, idler gear 52 is positioned between the interior of the belt and the free end of elbow 92 with shaft ends 100 seated in mating circular recesses 102 in flanges 104 attached to the outer longitudinal edges of the free end of elbow 92. The shaft ends 100 and mating recesses 102 are machined so that it requires slight pressure on the shaft ends to insert them into the recesses. With the aft belt loop and free end of elbow 92 in this position, as shown in FIG. 4., the belt will be loose and the idler gear 52 will float freely along the interior surface of the belt with the free end of elbow 92. This completes the cover plate assembly.

The free end of elbow 92 with the aft belt loop and idler gear 53 are now moved upwardly (as illustrated by the arrow in FIG. 4) to the operative position of the elbow by pressing the aft belt loop upwardly until it moves past its dead center position and that of the elbow substantially parallel to the longitudinal axis of the wrench, and continuing the pressure until the aft loop and free end of the elbow snap into seating position. This action stretches the belt 46 to a taut condition over the gears 44 and 52 so that the cover plate assembly can be assembled into housing channel 36 of the wrench body with the belt maintained in operating position with no danger of it coming off the gears 44 and 52 in assembly or while the wrench is being operated. The belt 46 in its taut condition is held flush against the interior surface of the top 51 of cover plate 50 to provide a movable closure for slide slot to prevent foreign material from entering the housing channel 36.

The fore end of elbow 92 is hinged-in depending flange 66 at a point below a line connecting the mounting points of the belt loops when the belt is substantially parallel to the longitudinal axis of the cover plate 50 and the loops are farthest apart. With this arrangement the aft end of elbow 92 in the aft loop of the belt 46 will reach its dead-center position when the gears 44 and 52 are farthest apart before the end of its travel toward its seating position, and upon slight further pressure in the direction of its seating position will seat by snap action therein. Seating slightly beyond dead-center position insures that the aft belt loop and free end of the elbow will not move out of the seated position during assembly of the cover plate assembly into housing channel 36 and during operation of the wrench.

It is obvious from the construction of the wrench that if the drive belt 46 becomes loose, assembly of the cover plate assembly into the housing channel 36 will be difficult. More importantly, there will be a lag between the movement of the belt by slide button 48 and movement of drive gear 44 and, correspondingly, movement of movable jaw 16 through intermediate gear 28, worm 26 and rack 24. Furthermore, if the belt is slack beneath slide slot 74, it is much easier for foreign material to enter the housing channel 36 through this slot. i

The elbow 92 may be constructed so that its effective radius can be adjusted by mounting it on an eccentric, making it of telescoping construction, or otherwise. This permits lengthening of the effective radius in ordr to render a belt taut which has become loose through wear, and affords accommodation of the elbow to wrenches using different belt lengths. The cover plate assembly including the drive belt assembly is now ready for insertion in slide channel 36.

The cover plate assembly is now assembled into the slide channel 36 by raising the aft end of the assembly so that lip 70 can be inserted under the roof 62 of circular recess 22 and the cover plate assembly is tilted axially in the direction of enlarged head 60 of the bevel gear 44 to permit the fore end of the cover plate assembly to move into position under the roof 62 of recess 22 with bevel gears 58 and 28 in mesh. The cover plate is then seated downwardly on shelf 38, and locking screw 106 screwed into position in a threaded hole in the upper surface of handle 18 to hold the assembly in position. Referring now to FIG. 3 it will be seen that when the slide button 48 is moved forward and backward the movable jaw will be moved open and shut, respectively.

FIG. 5 shows the manner in which drive belt 46 is secured to slide button 48 by means of pin 90.

In operation, when the jaws of the wrench are placed over a nut or other element to be turned, the slide button 48 is moved forwardly to rotate drive belt 46 which is in mesh with bevel gear 44 which is in turn in mesh with bevel gear 28 on the end of worm 26 so that worm 26 is rotated to move movable jaw 16 by means of rack 24 toward fixed jaw 14 against the nut. Thus complete adjustment can be made with the wrench in place and without its removal from the nut. In a corresponding reverse operation the jaws will separate on movement of the slide button rearwardly.

An advantage of the wrench described resides in the worm alignment feature by which the outwardly biased worm 26 is maintained in proper alignment at all times by the spring 35 and the alignment pin 34. This prevents wobbling or gyrating of the pin around its longitudinal axis with resultant decrease in wear of parts and loss of power transmitted by the drive belt. The main advantage of the wrench construction is the use of intermediate bevel gear 44 as a power transmission element between the drive belt 46 and the worm 26. By this construction no misalignment torque is imparted by the drive belt on the worm to resist its rotation and cause wear between the worm and the recess in which it is seated. Furthermore, there is very little loss of power between the drive belt and the worm by this construction. A final advantage of the wrench construction is the drive belt tightening and orienting feature by which the belt is held in taut position during assembly and operation to insure that it remains over the gears at all times and to prevent foreign material from entering the interior of the wrench through the slide slot.

I claim:

1. An adjustable jaw wrench comprising:

a. a body constructed as an integral handle, head and stationary jaw.

b. a movable jaw reciprocably mounted in said head in mating alignment with said fixed jaw;

c. rotatable driving means for said movable jaw mounted in said body in driving connection with said movable jaw for moving said movable jaw forward and backward;

d. a rotatable power transmission element separate from said rotatable driving means mounted in said body in driving connection with said rotatable driving means; and r e. a drive belt or chain extending into said handle drivingly connected to said rotatable power transmission element.

2. The adjustable jaw wrench of claim 1 in which said movable jaw includes an integral rack.

3. The adjustable jaw wrench of claim 1 in which said driving means is a worm.

4. The adjustable jaw wrench of claim 1 in which said power transmission element is a bevel gear.

5. The adjustable jaw wrench of claim 1 in which said driving means is a worm and said power transmission element is a bevel gear.

6. An adjustable jaw wrench comprising:

a. a body constructed as an integral handle, head and stationary jaw;

b. a movable jaw reciprocably mounted in said head in mating alignment with said fixed jaw and provided with an integral rack;

c. a worm rotatably mounted in said body in mesh with said rack;

d. a first bevel gear fixedly attached to said worm;

e. a second bevel gear rotatably mounted in said body with its teeth in mesh with the teeth of said first bevel gear; and

f. a drive belt extending into said handle drivingly connected to said second bevel gear.

7, The adjustable jaw wrench of claim 6 in which said first and second bevel gears are mounted at an acute angle to each other.

8. In an adjustable jaw wrench including a fixed jaw,

4O a head and a handle in which a worm is seated in a recess in the head drivingly connected to the movable jaw, a drive belt actuatable from the exterior of said wrench drivingly connected to said worm, in combination, alignment means including biasing means for said worm seated in said recess between the bottom of said recess and said worm, tightening means for tightening said drive belt comprising an elbow hinged at one end interiorly of said drive belt with its other end adapted to move with said drive belt from a position in which it renders said drive belt taut' to a position in which it renders said drive belt taut.

9. The adjustable jaw wrench of claim 8 including worm alignment means comprising a pin and spring mounted in said recess between the bottom of said recess and said worm with said alignment pin positioned between said spring and the bottom of said recess.

10. In an adjustable jaw wrench including a handle and movable and fixed jaws and power means including a looped endless drive belt mounted in a slide chamber in said handle for moving said movable jaw toward and away from said fixed jaw, in combination, tightening means for tightening said drive belt to maintain it in taut condition during assembly and operation of the wrench.

11. The adjustable jaw wrench of claim 10 in which said tightening means includes an elbow hinged at one end interiorly of said drive belt with its other end adapted to move with said drive belt from a first position in which it does not render the drive belt taut to a second position in which it renders said drive belt taut.

12. The adjustable jaw wrench of claim 11 in which said belt is provided with internal threads and an idler gear in mesh with said internal threads is mounted on said other end.

13. The adjustable jaw wrench of claim 12 in which said other end moves into said second position by snap action.

14. The adjustable jaw wrench of claim 13 including a cover plate with depending flanges and in which said one end is hinged to said flanges at a point below a line connecting the mounting points of said looped belt when the loops are farthest apart.

15. The adjustable jaw wrench of claim 11 including means for adjusting the efiective radius of said elbow.

16. In an open end adjustable jaw wrench of the type having a handle with a slide channel therein, a head including a fixed jaw, and a movable jaw driven by a worm seated in a worm recess in the head, in combination, a cover plate assembly including a cover plate for seating in said slide channel having a longitudinal slide slot therein, depending support means depending from said cover plate having seating means at its fore end for seating a gear, means at the fore end of said cover plate for attaching said cover plate to said head adjacent said worm recess, a drive gear seated in said seating recess with peripheral threads and being drivingly connected to said worm, an endless looped drive belt or chain oriented with fore and aft loops and provided with internal threads looped around said drive gear with said threads in mesh, an elbow hinged at one end in said depending support means interiorly of said looped belt, an idler gear mounted on the other end of the elbow with its threads in mesh with the internal thread of the belt, and a slide button for actuating said drive belt mounted for reciprocation in said slide slot.

17. A self-contained power assembly for actuating the movable jaw of an open end adjustable jaw wrench of the type having a handle with a slide channel therein, a head including a fixed jaw, and a movable jaw movable by a worm gear in a worm recess, comprising: a cover plate assembly including a cover plate for seating in said slide channel having a longitudinal slide slot therein, depending support means depending from said cover plate having seating means at its fore end for seating a gear, means at the fore end of said cover plate for attaching said cover plate to said head adjacent said worm recess, a drive gear seated in said seating recess having peripheral threads and being drivingly connected to said movable jaw, movable belt supporting means hingedly mounted in said depending support means, an endless drive belt with internal threads looped around said drive gear and said movable belt support means with said threads in mesh and a slide button for actuating said drive belt mounted for reciprocation in said slide slot.

18. A self-contained power assembly for actuating the movable jaw of an open end adjustable jaw wrench of the type having a handle with a slide channel therein, a head including a fixed jaw, and a movable jaw movable by a worm gear in a worm recess, comprising: a cover plate assembly including a cover plate for seating in said slide channel having a longitudinal slide slot therein, depending support means depending from said cover plate having seating means at its fore end for seating a gear, means at the fore end of said cover plate for attaching said cover plate to said head adjacent said worm recess, an endless drive belt oriented into fore and aft loops adapted to be connected to a belt actuating means having its fore loop drivingly connected to an intermediate gear which is drivingly connected to said worm, and a movable belt supporting means supporting said aft loop mounted in said depending support means interiorly of said looped belt.

19. An adjustable jaw wrench comprising:

a. a body constructed as an integral handle, head and stationary jaw;

b. a movable jaw reciprocably mounted in said head in mating alignment with said fixed jaw;

c. a worm rotatably mounted in a recess in said body in driving connection with said movable jaw;

d. alignment means in said recess for aligning said worm in operative orientation in said recess and,

e. a drive belt operable from the outside of said body extending into said handle and in driving connection with said worm, and a bevel gear rotatably mounted between said drive belt and said worm and in mesh with each. 

1. An adjustable jaw wrench comprising: a. a body constructed as an integral handle, head and stationary jaw. b. a movable jaw reciprocably mounted in said head in mating alignment with said fixed jaw; c. rotatable driving means for said movable jaw mounted in said body in driving connection with said movable jaw for moving said movable jaw forward and backward; d. a rotatable power transmission element separate from said rotatable driving means mounted in said body in driving connection with said rotatable driving means; and e. a drive belt or chain extending into said handle drivingly connected to said rotatable power transmission element.
 2. The adjustable jaw wrench of claim 1 in which said movable jaw includes an integral rack.
 3. The adjustable jaw wrench of claim 1 in which said driving means is a worm.
 4. The adjustable jaw wrench of claim 1 in which said power transmission element is a bevel gear.
 5. The adjustable jaw wrench of claim 1 in which said driving means is a worm and said power transmission element is a bevel gear.
 6. An adjustable jaw wrench comprising: a. a body constructed as an integral handle, head and stationary jaw; b. a movable jaw reciprocably mounted in said head in mating alignment with said fixed jaw and provided with an integral rack; c. a worm rotatably mounted in said body in mesh with said rack; d. a first bevel gear fixedly attached to said worm; e. a second bevel gear rotatably mounted in said body with its teeth in mesh with the teeth of said first bevel gear; and f. a drive belt extending into said handle drivingly connected to said second bevel gear.
 7. The adjustable jaw wrench of claim 6 in which said first and second bevel gears are mounted at an acute angle to each other.
 8. In an adjustable jaw wrench including a fixed jaw, a head and a handle in which a worm is seated in a recess in the head drivingly connected to the movable jaw, a drive belt actuatable from the exterior of said wrench drivingly connected to said worm, in combination, alignment means including biasing means for said worm seated in said recess between the bottom of said recess and said worm, tightening means for tightening said drive belt comprising an elbow hinged at one end interiorly of said drive belt with its other end adapted to move with said drive belt from a position in which it renders said drive belt taut to a position in Which it renders said drive belt taut.
 9. The adjustable jaw wrench of claim 8 including worm alignment means comprising a pin and spring mounted in said recess between the bottom of said recess and said worm with said alignment pin positioned between said spring and the bottom of said recess.
 10. In an adjustable jaw wrench including a handle and movable and fixed jaws and power means including a looped endless drive belt mounted in a slide chamber in said handle for moving said movable jaw toward and away from said fixed jaw, in combination, tightening means for tightening said drive belt to maintain it in taut condition during assembly and operation of the wrench.
 11. The adjustable jaw wrench of claim 10 in which said tightening means includes an elbow hinged at one end interiorly of said drive belt with its other end adapted to move with said drive belt from a first position in which it does not render the drive belt taut to a second position in which it renders said drive belt taut.
 12. The adjustable jaw wrench of claim 11 in which said belt is provided with internal threads and an idler gear in mesh with said internal threads is mounted on said other end.
 13. The adjustable jaw wrench of claim 12 in which said other end moves into said second position by snap action.
 14. The adjustable jaw wrench of claim 13 including a cover plate with depending flanges and in which said one end is hinged to said flanges at a point below a line connecting the mounting points of said looped belt when the loops are farthest apart.
 15. The adjustable jaw wrench of claim 11 including means for adjusting the effective radius of said elbow.
 16. In an open end adjustable jaw wrench of the type having a handle with a slide channel therein, a head including a fixed jaw, and a movable jaw driven by a worm seated in a worm recess in the head, in combination, a cover plate assembly including a cover plate for seating in said slide channel having a longitudinal slide slot therein, depending support means depending from said cover plate having seating means at its fore end for seating a gear, means at the fore end of said cover plate for attaching said cover plate to said head adjacent said worm recess, a drive gear seated in said seating recess with peripheral threads and being drivingly connected to said worm, an endless looped drive belt or chain oriented with fore and aft loops and provided with internal threads looped around said drive gear with said threads in mesh, an elbow hinged at one end in said depending support means interiorly of said looped belt, an idler gear mounted on the other end of the elbow with its threads in mesh with the internal thread of the belt, and a slide button for actuating said drive belt mounted for reciprocation in said slide slot.
 17. A self-contained power assembly for actuating the movable jaw of an open end adjustable jaw wrench of the type having a handle with a slide channel therein, a head including a fixed jaw, and a movable jaw movable by a worm gear in a worm recess, comprising: a cover plate assembly including a cover plate for seating in said slide channel having a longitudinal slide slot therein, depending support means depending from said cover plate having seating means at its fore end for seating a gear, means at the fore end of said cover plate for attaching said cover plate to said head adjacent said worm recess, a drive gear seated in said seating recess having peripheral threads and being drivingly connected to said movable jaw, movable belt supporting means hingedly mounted in said depending support means, an endless drive belt with internal threads looped around said drive gear and said movable belt support means with said threads in mesh and a slide button for actuating said drive belt mounted for reciprocation in said slide slot.
 18. A self-contained power assembly for actuating the movable jaw of an open end adjustable jaw wrench of the type having a handle with a slide channel therein, a head including a fixed jaw, and a movable jaw movable by a worm gear in a worm recess, comprising: a cover plate assembly including a cover plate for seating in said slide channel having a longitudinal slide slot therein, depending support means depending from said cover plate having seating means at its fore end for seating a gear, means at the fore end of said cover plate for attaching said cover plate to said head adjacent said worm recess, an endless drive belt oriented into fore and aft loops adapted to be connected to a belt actuating means having its fore loop drivingly connected to an intermediate gear which is drivingly connected to said worm, and a movable belt supporting means supporting said aft loop mounted in said depending support means interiorly of said looped belt.
 19. An adjustable jaw wrench comprising: a. a body constructed as an integral handle, head and stationary jaw; b. a movable jaw reciprocably mounted in said head in mating alignment with said fixed jaw; c. a worm rotatably mounted in a recess in said body in driving connection with said movable jaw; d. alignment means in said recess for aligning said worm in operative orientation in said recess and, e. a drive belt operable from the outside of said body extending into said handle and in driving connection with said worm, and a bevel gear rotatably mounted between said drive belt and said worm and in mesh with each. 